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How To Calculate Fertilization Date Using Ultrasound And Menstrual Cycle?

Posted on Tue, 20 May 2014

Question: If I had my period on March 10th, and then had unprotected sex every weekend after with the last encounter being march 31rst, in which he didn't orgasm and I took morning after pill 8 hrs later. Then 5 days later on April 5th, I took an at home pregnancy test and was positive. Then on April 18th had adapting ultrasound d and it dated me a 5 weeks 4 days. What is the likelihood it was caused by the march 31rst encounter?!?

Answered by Dr. Mahesh Koregol (48 minutes later)

Brief Answer:
Yes

Detailed Answer:
Hi,

I read your query and I understand your concerns.

Following is my reply:

1) You are right. It is likely to be from March 31 encounter.

2) The dates you have mentioned corresponds to that.

Let me know if you have any more doubts.

Regards,

Dr. Mahesh Koregol
IVF & infertility Specialist

Above answer was peer-reviewed by : Dr. Chakravarthy Mazumdar

Follow up: Dr. Mahesh Koregol (2 minutes later)

Wait... So your telling me it was the march 31rst encounter in which I got pregnant. How is that possible, when I had a positive test just 5 days after and 19 days they gave me a dating ultrasound at 5 weeks 4 days.

Answered by Dr. Mahesh Koregol (7 minutes later)

Brief Answer:
ulrasound

Detailed Answer:
Hi,

1.The ultrasound scan is more accurate in predicting gestational age especially early scan as yours.

2. The chances of false positive of urine pregnancy test is higher than accuracy of ultrasound. So ultrasound is more reliable.

3. Your cycle was on March 10th. So you can ovulate only after 25th March ( After 15 days from LMP ) which makes 31st March as nearest date.

Regards

Above answer was peer-reviewed by : Dr. Chakravarthy Mazumdar

Follow up: Dr. Mahesh Koregol (2 minutes later)

I have asked 15 drs on here and you are the only one tat said it could be march 31rst.

I'll submit my question again.

Answered by Dr. Mahesh Koregol (2 minutes later)

Brief Answer:
ok

Detailed Answer:
Hi,

If you calculate your ovulation date and the frequency of sex you had, it corelates with ultrasound report.

Early scan is always used as a guide in dating scan when the dates are a confusion. Urine pregnancy test is not relied upon

Regards

Above answer was peer-reviewed by : Dr. Chakravarthy Mazumdar